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City of Waco Wastewater Master Plan

City of Waco Wastewater Master Plan

Challenge
The City of Waco retained the Team of Walker Partners, HDR, and Burgess & Niple to develop a Wastewater Master Plan for the City’s wastewater collection system. Waco’s last comprehensive Wastewater Mater Plan was conducted in 1975. In 2000, as part of the Comprehensive Plan, three broad-based wastewater planning recommendations were presented as part of the overall Comprehensive Plan; however, neither the objective nor the intent of that effort was to identify inadequacies or risks in the existing wastewater system. Since the time that the aforementioned studies were completed, the City’s wastewater collection system has aged and grown in size and complexity, while the population and land development have increased.

Solution 
Significant effort was spent in order to ascertain the actual wastewater flows within the collection system during rainfall events. Old sanitary sewer systems are not watertight, and during heavy rains storm water enters the sanitary sewers, loads the pipes, and causes sewage spills in the creeks and rivers. The work included the temporary metering of the sewer system used to calibrate the computer model with the “real world” data. This metered flow data enables the City staff to better understand their existing system and better manage the day-to-day operations. The Master Plan evaluates, in detail, the capacity of the existing system, the structural integrity and projected longevity of the system, and the consequences of failure of the components of the existing system. This effort will enable city planners and engineers to manage budgets, growth, and capital improvement projects for the next two decades.

Value
The Wastewater Collection System Master Plan report has been prepared to provide the City of Waco a road map that will serve as a guide for short-term and long-term improvements to the wastewater system infrastructure. The plan will provide the City with a strategy to not only preserve previous investments in the existing sanitary sewerage infrastructure, but to plan for the future needs of a growing City. The key objectives in preparing this roadmap are summarized as follows:

  • Capture, document, and map historical and institutional knowledge of the system
  • Develop comprehensive and accurate population and flow projections
  • Analyze the existing sanitary sewer system
  • Protect the City’s water supply
  • Develop a prioritized Capital Improvement Program

The Capital Improvement Program provides the “roadmap” to improve the existing wastewater collection system and accommodate projected wastewater flows through 2040. Combinations of improvements were evaluated at various locations in order to establish the most appropriate approaches for implementation. These evaluations included considerations to increase system reliability, to simplify system operations, to handle peak wet weather flows, to reduce sanitary sewer overflows, and to assist staff in the operation and management of the wastewater collection system. The projects will move the City towards a more reliable and efficient wastewater system. It is understood that a Capital Improvement Program that doesn’t assist the Water Utilities staff in operating and managing their system is not considered to be a good plan. The program will also assist staff in planning and prioritizing future wastewater projects to accommodate redevelopment of existing urbanized areas; to promote longevity and redundancy of the current sanitary sewer system; to rehabilitate sections of pipe that have outlived their design life; and to maximize the return on investment for each improvement project. The total cost of the 10-Year Capital Improvement Program is $245,000,000.